The present invention relates to metallic containers and, more particularly, to metal container having an anode for protection of the container and for prevention of undesired chemical reaction between the material of the container and the contents stored therein.
It has long been recognized that packaging of certain corrosive food-stuffs, notably ham in brine, in steel cans or containers, results in corrosion problems. Specifically, the brine solution attacks any exposed metal of the container, while contact between exposed metal and the ham results in discoloration of the meat.
Attempts to solve this problem have centered around provision of a protective inner coating on the container walls or provision of a sacrificial anode.
Reliance solely on a protective inner coating has proven unsuccessful in that such a coating must maintain absolute integrity to be effective. This integrity is generally destroyed during formation of this sideseam of a three piece can and/or during attachment of the bottom and top of the can to the container side wall. For this reason, greater reliance is currently placed upon provision of a sacrificial anode on the interior of the container.
Successful use of a sacrificial anode has been hampered by lack of a satisfactory means of attaching the anode to the container wall. Attempts at spot welding the anode to the wall have proven unsatisfactory in that the lacquer protective coating on the inner surface of the container wall interferes with a successful weld. It is therefore necessary to remove all lacquer in the area of the weld to insure a reliable attachment. This involves an unacceptable additional expense. Mechanical fastening of the anode to the container wall has also proven unsatisfactory in that the process tends to leave exposed metal on the container wall which is not covered by the anode. The exposed metal of the container may then come in contact with the product resulting in an undesirable discoloration thereof. Existing methods of anode attachment are further found to be unreliable, allowing separation of the anode from the container or loss of electrical contact between the anode and the container body during post-attachment handling.